EP3773351B1 - Orthesis or prosthesis system for open-loop or closed-loop orthesis or prosthesis control - Google Patents

Description

The invention relates to an orthotic or prosthetic system.

An orthosis within the meaning of the invention is an aid that is used to stabilize, relieve, immobilize, guide or correct a part of the body. A prosthesis within the meaning of the invention is an aid that replaces a part of the body.

In medicine, orthoses and prostheses are used as supplementary aids or as a replacement for limbs and organs. Conceptually, orthoses and prostheses cannot always be separated, especially since some orthoses also replace unusual body functions. This is why the term "orthoses or prostheses" is always used in the following. It is of course possible to use the subject matter of the invention only with a prosthesis or only with an orthosis.

The starting point for considerations about orthosis or prosthesis control or regulation is the wish of the user of an orthosis or prosthesis not to perceive them as a disadvantage or a handicap, but in daily use in the case of an orthosis as support or relief for the part of the body to be checked or in the case of the case to be able to use a prosthesis as a complete replacement for the missing part of the body.

The orthotic or prosthetic system should therefore compensate for the limitations of the user in the best possible way or create a replacement that prevents limitations. Requirements for an orthotic or prosthetic system are, for example, the maintenance or restoration of the user's motor skills and suitability for everyday use. As many degrees of freedom of movement as possible enable the user to compensate for restrictions particularly well. In the case of an orthotic or prosthetic system within the meaning of the invention, the orthotic or prosthesis is combined with a sensor system and an actuator system, which can be jointly inserted into a control sequence or also into a control loop.

In the usual sense, sensors and actuators are understood to mean the acquisition of signals or the triggering of movements by signals.

To control or regulate orthotics or prostheses, the user's desire to move must be determined as quickly and reliably as possible. This is usually done through the acquisition of muscle-related signals. Muscle-related signals are understood here, in particular electrical signals, which relate to a state of a muscle, in particular to the strength and / or direction of the contraction of the muscle or to the direction and / or speed of the movement of the muscle.

Of particular importance is the interference immunity of the recorded muscle-related signals, which are used for the regulation in order to prevent malfunctions of the orthotic or prosthetic system.

In the prior art, various methods for recording muscle-related signals are known that can be used to control or regulate orthoses or prostheses:
the DE 10 2008 002 933 A1 shows a data recording for patient analysis, as it can be used with conventional prostheses. The electrical activity of the muscles or muscle groups is recorded and analyzed at a few, mostly two locations using different surface electrodes, for example by means of electromyography (EMG).

Another well-known method for detecting muscle activity is mechanomyography (MMG), in which the vibrations that arise when the muscles are tensed are measured.

Scientific publications also show that the amount of complex electrical bioimpedance is also influenced by muscle contractions (cf. Soo- Chan Kim: Estimation of Hand Gestures Using EMG and Bioimpedance, The Transactions of the Korean Institute of Electrical Engineers, Vol. 65, No. 1, pp. 194-199, 2016, ISSN 1975-8359 (Print) / ISSN 2287-4364 (Online), http://dx.doi.org/10.5370/KIEE.2016.65.1.194 ), whereby the discussion is limited to the manner of possible measurements with sensors or electrodes and the interpretation of measurement results.

From the WO 2017/160183 A1 a method for bionic control of a technical device, such as an exoskeleton or a prosthesis, is known. Electrophysiological signals from a contracting muscle are recorded using electrodes and sent to a control device. To record the electrophysiological signal, a voltage is applied to the muscle and a change in the electrical impedance during muscle contraction is recorded and used as a signal.

The invention is based on the object of providing an orthotic or prosthetic system which in each case has an improved immunity to interference. In particular, it is desirable to be able to differentiate as well as possible between disruptive influences and actual muscle contraction.

This object is achieved by an orthotic or prosthetic system according to claim 1. Advantageous embodiments of the invention are contained in the subclaims.

The orthosis or prosthesis system under consideration has the following components: at least one orthosis or prosthesis, at least one pair of electrodes which are provided for contacting the body of the user of the orthosis or prosthesis, for recording muscle-related signals, at least one evaluation unit for the at least one pair of electrodes detected muscle-related signals, at least one actuator for moving the at least one orthosis or prosthesis and at least one control unit for controlling the at least one actuator.

According to a first aspect of the invention, this is at least one pair of electrodes set up to acquire at least a first muscle-related signal using a first measurement frequency and a second muscle-related signal using a second measurement frequency. In addition, the at least one evaluation unit is set up to evaluate a phase of the respective first signal and a phase of the respective second signal. The evaluation of the phase of the respective first signal and the phase of the respective second signal can make it possible to distinguish a “real” muscle-related signal from an interference signal.

In a preferred embodiment of the invention, the respective evaluation unit is set up to evaluate a phase curve of the respective first and respective second signal. As will be described below, the phase profile of a muscle-related signal can have certain characteristics which do not occur in the case of an interference signal. In this way, a "real" muscle-related signal can be distinguished from any other type of signal, called a disturbance signal here.

• eine Phase des jeweiligen ersten Signals mit einer, insbesondere frequenzabhängigen, Referenzphase zu vergleichen, um eine erste Phasenveränderung wenigstens qualitativ zu ermitteln;
• eine Phase des jeweiligen zweiten Signals mit der, insbesondere frequenzabhängigen, Referenzphase zu vergleichen, um eine zweite Phasenveränderung wenigstens qualitativ zu ermitteln; und
• die erste Phasenveränderung und die zweite Phasenveränderung auszuwerten, insbesondere miteinander zu vergleichen.

The respective evaluation unit is set up for this:

• to compare a phase of the respective first signal with a, in particular frequency-dependent, reference phase in order to determine a first phase change at least qualitatively;
• to compare a phase of the respective second signal with the, in particular frequency-dependent, reference phase in order to determine a second phase change at least qualitatively; and
• to evaluate the first phase change and the second phase change, in particular to compare them with one another.

As a result, the characteristics of a real muscle-related signal or an interference signal can be recognized and evaluated.

In a preferred embodiment, the reference phase is a phase, in particular a previously determined phase, which essentially corresponds to a measurement in a relaxed state of a muscle.

Using such a reference phase can help ensure that the signals are correctly identified.

According to a preferred embodiment, the evaluation unit is set up to determine whether the first phase change is a phase change in the same direction as the second phase change, or in an opposite direction.

The directions of the first and second phase change can be used to distinguish between real muscle-related signals and interference signals.

According to one embodiment, the evaluation unit is set up to evaluate the first and second signals as belonging to a muscle contraction when the first and second phase changes are phase changes in opposite directions.

In this way, a real muscle-related signal can be reliably recognized.

Correspondingly, according to one embodiment, the evaluation unit can be set up to evaluate the first and second signals as belonging to a disturbance if the first and second phase changes are phase changes in the same direction.

In this way, a malfunction or an interfering signal can be correctly identified.

According to one embodiment, the first measurement frequency is more than approx. 60 kHz and the second measurement frequency is less than approx. 60 kHz.

The inventors have found that the phase profile below a frequency of approx. 60 kHz differs from the phase profile above a frequency of approx. 60 kHz, depending on whether the signal to be evaluated is a real muscle-related signal or an interference signal. A reliable differentiation can therefore be made for a measurement below and above approx. 60 kHz.

According to a preferred embodiment, the first measurement frequency is significantly greater than 60 kHz and / or the second measurement frequency is significantly smaller than 60 kHz. This allows the distinction between the two types of signals to be made with even greater reliability.

In a preferred embodiment of the invention, the at least first and second muscle-related signal is a (complex) bioimpedance signal.

The characteristic phase behavior described above occurs in particular in the case of a bioimpedance signal.

In a preferred embodiment of the invention, the at least one pair of electrodes is also set up to supply electrical stimulation signals to the user of the orthosis or prosthesis. By using the same pair of electrodes as for the signal measurements, the outlay on equipment is reduced, and it is ensured that the stimulation signals are supplied exactly at the measurement location of the signal measurements and are therefore carried out in the area of the same muscle to which the signal measurements are based.

In a preferred variant of this embodiment, the electrical stimulation signals are set up to give the user of the orthosis or prosthesis feedback about the movements and / or the state of the orthosis or prosthesis. Movement or state parameters to which the feedback can relate are, in particular, the speed of the orthosis or prosthesis or the force generated by it. In this way, for example, the user of a hand prosthesis can be informed of how forcefully the prosthesis is gripping.

A modular retrofitting of existing orthotic or prosthetic systems is possible.

The orthotic or prosthetic system according to the invention can thus be used for a wide variety of applications in medical technology.

In particular, the invention enables an improvement in the interference immunity of the orthotic or prosthesis control through the acquisition of at least two muscle-related signals with different measurement frequencies. Since the two signals can be recorded by the same pair of electrodes, the outlay on equipment can be reduced, and it can be ensured that the two signals are measured precisely at the same location.

Although the inventors consider the measurement of two signals using different measurement frequencies according to the first aspect of the invention to be particularly reliable, measurement of only one signal, i.e. with only one measurement frequency, and subsequent evaluation of the phase of the measured signal may be possible be enough.

It is preferred here that the first measurement frequency is significantly greater than 60 kHz and / or the evaluation unit is set up to compare a phase of the first signal with an, in particular frequency-dependent, reference phase in order to determine a first phase change at least qualitatively.

This allows the distinction between real muscle-related signals and interference signals to be made with just one measurement with sufficient reliability.

In a method for controlling or regulating an orthotic or prosthesis by an orthotic or prosthetic system according to the invention, a first and a second muscle-related signal are recorded by the at least one pair of electrodes and their phase is evaluated by the at least one evaluation unit, one phase of the first signal is compared with a, in particular frequency-dependent, reference phase in order to determine a first phase change; a phase of the second signal is compared with the, in particular frequency-dependent, reference phase in order to determine a second phase change; and the first phase change and the second phase change are evaluated, in particular compared with one another. In addition, the at least one actuator is controlled as a function of the result of the evaluation of the phases of the at least first and second muscle-related signals and the orthosis or prosthesis is moved by the at least one actuator.

The method can provide fast and simple signal processing for an orthotic or prosthetic system according to the invention.

In addition to classic orthotics and prosthetics, the method and system presented here can also be used to control information technology, such as B. PC, game console or similar application to facilitate / enable the user to operate them. The signals obtained from the human muscle can also be used in conjunction with a mechatronic device for electromechanical reinforcement of the muscles.

Fig. 1

einen Teil eines Orthesen- oder Prothesen-Systems in schematischer Darstellung nach einer Ausführungsform;

Fig. 2

den Verlauf des Betrages eines Bioimpedanzsignals bei verschiedenen Messfrequenzen;

Fig. 3

den Verlauf der Phase eines Bioimpedanzsignals bei verschiedenen Messfrequenzen;

Fig. 4

den Verlauf des Betrages eines Bioimpedanzsignals bei verschiedenen Messfrequenzen, und

Fig. 5

den Verlauf der Phase eines Bioimpedanzsignals bei verschiedenen Messfrequenzen.

Further features, advantages and possible applications of the invention emerge from the following description in connection with the respective figure. Show:

Fig. 1

a part of an orthotic or prosthetic system in a schematic representation according to one embodiment;

Fig. 2

the course of the amount of a bioimpedance signal at different measurement frequencies;

Fig. 3

the course of the phase of a bioimpedance signal at different measurement frequencies;

Fig. 4

the course of the amount of a bioimpedance signal at different measurement frequencies, and

Fig. 5

the course of the phase of a bioimpedance signal at different measurement frequencies.

Fig. 1 shows part of an orthotic or prosthetic system 100 according to an embodiment of the present invention. Links in Fig. 1 an arm is indicated with skin 1 and muscle 2. Although the system according to the invention is mainly described with reference to an arm, it goes without saying that the orthotic or prosthetic system can also be used with other parts of the body. It is also understood that the muscle 2 described here is representative of muscles or muscle groups.

A set of electrodes 11 of the orthotic or prosthetic system 100 contact the skin 1, the electrode set in the example shown consisting of four electrodes 11, namely two electrodes each, which are used to impress current, and two electrons for voltage measurement. The bioimpedance can be determined in a manner known per se from the measured voltage and the current measured or known in advance.

The orthosis or prosthesis itself is not in Fig. 1 shown. If necessary, as in Fig. 1 shown, further sensors and / or further actuators 12 may be present and, if necessary, contact the skin 1.

The electrodes 11 are connected to an evaluation unit 10, where the current and voltage signals can be further processed and / or stored. The right part of the Fig. 1 illustrates schematically the further processing of the current and voltage signals or the further processing of signals derived from the current and voltage signals. These functions can be implemented either in the evaluation unit 10 or in an evaluation unit (not shown) coupled to it.

As will be explained in more detail below, the phase ϕ and the amount | Z | the bioimpedance Z can be determined and further processed. Optionally, as in Fig. 1 indicated, other measured variables, such as an electromyography (EMG) and / or mechanomyography signal (MMG), are determined and, if necessary, further processed.

The inventors have recognized that both the amount | Z | as well as the phase ϕ of the bioimpedance changes during a muscle contraction. They found that the phase change as a function of the measurement frequency has a characteristic which can be used to distinguish between "real" muscle-related signals and interference signals. The term “real” muscle-related signals is preferably understood to mean that these are signals that can be traced back to an actually occurring muscle contraction or the like. In contrast to this, interfering signals are preferably those signals which are at least partially, preferably predominantly, and more preferably essentially exclusively, due to interfering influences. Such a disruptive influence can be, for example, inadequate contact between an electrode 11 and the skin 1.

Fig. 2 shows an example of the frequency response of the amount | Z | the bioimpedance as a function of the measurement frequency f used for a part of the body. The upper curve 20 shows the course of the amount | Z | the bioimpedance in a relaxed state of the muscle and the lower curve 21 the course of the amount | Z | the bioimpedance during a muscle contraction. As Fig. 2 clearly shows, the amount | Z | decreases the bioimpedance during a muscle contraction in the entire frequency range shown.

In the Fig. 3 The illustrated phase ϕ of the bioimpedance has a different profile in the frequency range shown. The curve, which corresponds to a relaxed muscle state, is provided in a left area with the reference number 22 and in a right area with the reference number 26. The curve sections 25 and 24 represent the phase of the bioimpedance during a muscle contraction. As in FIG Fig. 3 As can be clearly seen, the curve 22, 26 intersects the curve 24, 25 at a point 23. This means that the phase at a measurement frequency which corresponds to the intersection point 23 (approx. 60 kHz) is due to a muscle contraction compared to the relaxed one State does not change. At lower measurement frequencies (to the left of the intersection 23), the phase ϕ of the bioimpedance decreases due to a muscle contraction. In contrast, the phase ϕ increases at higher measurement frequencies (to the right of the intersection 23) due to a muscle contraction.

To the Fig. 3 (and accordingly also to the one explained below Fig. 5 ) it should be noted that reducing the phase here means that the phase is "even more negative" will. The amount of the phase increases with the in Fig. 3 the illustrated decrease in phase.

The in Fig. 3 The illustrated frequency response of the phase ϕ of the bioimpedance can be evaluated according to exemplary embodiments of the present invention in order to recognize a muscle contraction and in particular in order to distinguish it from an interference signal. The control unit, which controls the actuator in order to move the orthosis or prosthesis, can then be operated as a function of a result of the evaluation carried out with the evaluation unit 10.

With regard to the measurement of the bioimpedance and the evaluation of the phase of the bioimpedance, there are several variants that are briefly described here. In the following, the term "cut frequency", abbreviated fs, is referred to several times. This cutting frequency corresponds to the measurement frequency at the point of intersection 23, it being possible for this to be different under certain circumstances for different muscles or for different people. If necessary, this cut frequency could be determined empirically on a case-by-case basis.

Version 1:

The bioimpedance or the phase ϕ of the bioimpedance are measured at two different measuring frequencies f1 and f2, where f1 is smaller, in particular significantly smaller than fs, and where f2 is larger, in particular significantly larger than fs. The phases ϕ1 and ϕ2 for the measurement frequencies f1 and f2 result from these measurements. The phases ϕ1 and ϕ2 are then compared in the evaluation unit 10 with a reference phase ϕR. The reference phase ϕR can have been stored in the evaluation unit 10 in advance. The reference phase ϕR can in particular be the phase ϕ of the bioimpedance in the relaxed muscle state, that is to say as shown by curve 22, 26. Although it can make sense to determine and save the reference phase ϕR for many different frequencies, it would also be possible to determine and save the reference phase ϕR only for the two measurement frequencies f1 and F to be used.

In the evaluation unit 10, in particular by a comparator 13 ( Fig. 1 ), the phases ϕ1 and ϕ2 with corresponding reference phases ϕR1 and ϕR2 compared. Such a comparison can be used to determine a phase change or phase difference ϕD1 and ϕD2. This phase change or phase difference therefore corresponds to the change in the phases caused by the muscle contraction at the respective measurement frequencies. If the comparator 13 detects phase changes in different directions for the two measurement frequencies (or phase differences with different signs), the signal measured by the electrodes 11 is evaluated as a real signal of a muscle contraction.

If, on the other hand, the comparator 13 detects phase changes in the same direction or phase differences with the same sign, the signal measured by the electrodes 11 is evaluated as an interference signal, or at least not as belonging to a muscle contraction.

If no phase change or difference can be determined, or if the phase change or difference has not exceeded a minimum value, the signal is not assessed as belonging to a muscle contraction, i.e. in this case the measurement is preferably interpreted in such a way that the muscle is in a relaxed state is.

Variant 2:

The second variant differs from the first in particular in that one of the measurement frequencies f1, f2 is in the vicinity of the cutting frequency fs, in particular is essentially the same as the cutting frequency. The evaluation is adjusted accordingly. This means, in particular, that a signal detected by the electrodes 11 is evaluated as a real muscle-related signal if a phase change or phase difference is determined for the measurement frequency, which differs (significantly) from the cutting frequency fs, and for the other measurement frequency, which is close to or is equal to the cutting frequency fs, but no or only a very small phase change or difference is determined.

In contrast, the signal is assessed as not belonging to a muscle contraction if there is no or only a very slight change for both measurement frequencies the phase, or if there is a phase change in the same direction for both measurement frequencies.

In the first and second variant, it would be possible to carry out the evaluation only qualitatively, i.e. only to determine in which directions the phases change (or whether there is any phase change at all) without (further) taking into account the size of the change. Such a qualitative evaluation would be sufficient to distinguish a real muscle-related signal from an interfering signal.

Variation 3:

This variant is similar to the second variant. In the third variant, the measurement frequencies f1 and f2 are selected so that either both are greater or both are less than the cutting frequency fs. However, one of the frequencies should be much closer to the cut frequency than the other. According to this variant, however, it would be necessary to evaluate the phase change or phase difference not only qualitatively (phase change in the same or different directions, phase differences with the same or different signs, no significant phase change), but also quantitatively, because it would be expected that with a muscle contraction the phases at the different measurement frequencies would change in the same direction, but the size of the changes would be different.

Variation 4:

According to this variant, it is sufficient to determine and evaluate only one phase, i.e. only at one measuring frequency. The measuring frequency is preferably above the cutting frequency fs and is in particular significantly higher than the cutting frequency fs, that is to say in a frequency range for the in Fig. 3 curve 24 (muscle contraction) is significantly higher than curve 26 (relaxed state). Again, the phase change is evaluated relative to a reference phase, for example by forming a phase difference. This can in turn be carried out in the comparator 13. If the comparator 13 determines that the phase determined from the measurement is greater than the reference phase, the signal is evaluated as belonging to a muscle contraction. Otherwise it will The signal is evaluated either as an interference signal (the phase determined from the measurement is smaller than the reference phase) or as belonging to a relaxed muscle (no phase change).

Further explanations

It has already been mentioned that orthotic or prosthetic systems according to embodiments of the invention can recognize real muscle-related signals, i.e. in particular signals attributable to a muscle contraction, with greater reliability and, in particular, can distinguish them from interference signals than was possible according to approaches in the prior art . In this context, it is useful to explain the course of the amount | Z | the bioimpedance or the phase ϕ of the bioimpedance of a possible interference signal. In this context, the Figures 4 and 5 Referenced.

Fig. 4 shows the frequency-dependent course of the amount | Z | the bioimpedance for a given muscle condition. Here, the lower curve 28 shows the course with good electrode-skin contact of the negative current electrode and curve 27 shows the course with poor electrode-skin contact. A bioimpedance that is larger in amount (upper curve 27) thus corresponds to a poorer contact than a bioimpedance that is smaller in amount (lower curve 28). An evaluation of the signals that relate solely to the amount | Z | that supports bioimpedance, but could give unreliable results under certain circumstances. For example, an increase in the amount of bioimpedance can either mean that the muscle has relaxed (more) compared to a comparison state, or that the electrode-skin contact has worsened.

Fig. 5 shows the frequency response of the phase of bioimpedance in the case of good electrode-skin contact (upper curve 29) and in the case of poor electrode-skin contact (lower curve 30). The in Fig. 5 The frequency response of the phase shown does not have that in Fig. 3 characteristic frequency response shown for real muscle-related signals. In particular, the curves 29 and 30 do not intersect. The differences between a real muscle-related signal ( Fig. 3 ) and an interfering signal, such as poor electrode-skin contact ( Fig. 5 ), become particularly clear if a measurement and evaluation is carried out according to the first variant described above. In the two measurements with the two measurement frequencies f1 and f2 (with f1 <fs <f2), the evaluation described above provides a phase change in different directions for a real muscle-related signal. For an interfering signal, such as a deterioration in the electrode-skin contact, on the other hand, it provides a phase change in the same direction. Due to this fact, the evaluation unit 10 can distinguish between a real muscle-related signal and an interference signal.

The same applies to the other variants described above.

According to embodiments of the invention, two or more measurements can be carried out at two or more different frequencies by means of the same set of electrodes 11 (using more than one measuring channel). The measurements could be carried out quasi-simultaneously, i.e. with short intervals that are not noticeable to a user. Alternatively, the measurements could be made at the two or more different frequencies using different sets of electrodes.

As in Fig. 1 As shown, the evaluation unit 10 according to the embodiment shown has an A / D converter (ADC) 14, which converts the determined phase of the bioimpedance and possibly also the amount of bioimpedance and / or other measured or derived variables into a digital format. The digital data output by the A / D converter can be temporarily stored in an intermediate memory (buffer) 15 and, if necessary, further processed by an extended signal processing unit 16. In particular, such further processing can include controlling an actuator for moving the orthosis or prosthesis.

Fig. 1 indicates yet another advantage of embodiments of the invention. Embodiments of the invention provide that additional measuring methods and / or signal processing components are only switched on when a muscle contraction has been detected by means of the method described above, in particular by the comparator 13. This is in Fig. 1 indicated by an arrow that of the comparator 13 goes out and leads to the symbol of an on / off switch 17 of the unit 16. In this way, processes or components with, under certain circumstances, a comparatively high energy requirement can be carried out or operated in a more energy-saving manner, which can reduce the energy requirement of the entire system. As a result, the battery capacity of the orthosis or prosthesis or of the orthosis or prosthesis system can possibly be saved, which can also lead to advantages in production.

According to a further embodiment of the invention, it is possible to arrange several electrodes (sets) 11 in an electrode array. This enables a high geometric resolution to be achieved.

• Kostengünstiges System, beispielsweise dadurch, dass kein (signifikant) höherer Schaltungsaufwand im Vergleich zu bereits bekannten Systemen entsteht
• (Signifikante) Erhöhung der Messsicherheit von Muskelkontraktionen und bessere Erkennung des Nutzerwunsches nach einer Prothesenbewegung
• Geringe Anzahl von Elektroden notwendig

Advantages (or further advantages) of at least some embodiments of the invention are:

• Inexpensive system, for example in that there is no (significantly) higher circuit complexity compared to already known systems
• (Significant) increase in the measurement reliability of muscle contractions and better recognition of the user's wish for a prosthesis movement
• Small number of electrodes required

• Wie die anderen Komponenten auch, kann der Vergleicher sowohl digital, als auch analog realisiert werden.
• Zusätzlich kann das Verfahren um die Information der Bioimpedanz-Betragsänderungen bei Muskelkontraktion erweitert werden.
• Das anisotrope Impedanzverhalten von Muskelgewebe kann ausgenutzt werden, indem mehrere (quasi-)simultane Messungen an der gleichen Muskelgruppe in unterschiedlichen geometrischen Elektroden-Anordnungen durchgeführt werden.
• Messung des Zustands der Elektrode-Haut-Übergänge. Aus dieser Information kann auch geschlossen werden, wie zuverlässig die zusätzliche Messung des EMG-Signals ist.
• Mittels der Bioimpedanzmessung kann auch die arterielle Pulswelle detektiert werden. Aus dieser lassen sich Informationen wie Herzschlagfrequenz, Pulswellengeschwindigkeit, Augmentationsindex, Blutdruck und Atemfrequenz ableiten.
• Der entstehende Informationsgewinn durch das Messen bei mindestens 2 Frequenzpunkten liefert zusätzliche Informationen über die Kontraktionsstärke.

Possible extensions / variants:

• Like the other components, the comparator can be implemented digitally as well as analog.
• In addition, the method can be expanded to include information on changes in the amount of bioimpedance in the event of muscle contraction.
• The anisotropic impedance behavior of muscle tissue can be exploited by carrying out several (quasi-) simultaneous measurements on the same muscle group in different geometric electrode arrangements.
• Measurement of the state of the electrode-skin junctions. This information can also be used to determine how reliable the additional measurement of the EMG signal is.
• The arterial pulse wave can also be detected by means of the bioimpedance measurement. From this information such as heart rate, Derive pulse wave velocity, augmentation index, blood pressure and respiratory rate.
• The resulting information gain by measuring at least 2 frequency points provides additional information about the contraction strength.

Possible areas of application of the invention include prosthetics, orthotics, human-machine interfaces for controlling computers, machine control and controlling exoskeletons.

List of reference symbols

1

skin

2

muscle

10

Evaluation unit

11

Pair of electrodes

12th

further sensors / actuators

13th

Comparator

14th

A / D converter

15th

Cache

16

Signal processing unit

17th

counter

20,21,27,28

Measurement curves (amount of bioimpedance)

22.24-26.29.30

Measurement curves (phase of bioimpedance)

100

Orthosis or prosthesis system

Claims (11)

1. An orthosis or prosthesis system (100), comprising

   - at least one orthosis or prosthesis,

   - at least one pair of electrodes as an electrode pair (11), provided for contacting the body (1) of the user of the respective orthosis or prosthesis for the purpos of detecting muscle-related signals,

   - at least one evaluation unit (10) for muscle-related signals detected by the at least one electrode pair (11),

   - at least one actuator (12) for moving the respective at least one orthosis or prosthesis, and

   - at least one control unit for controlling the at least one actuator (12), wherein the at least one electrode pair (11) is configured to detect at least a first muscle-related signal using a first measurement frequency and a second muscle-related signal using a second measurement frequency and the at least one evaluation unit (10) is configured to evaluate a phase of the first signal and a phase of the second signal characterized in that the evaluation unit (10) is configured:

   - to compare a phase of the first signal to a reference phase, in particular to a frequency-dependent reference phase, in order to ascertain a first phase change;

   - to compare a phase of the second signal to the reference phase, in particular to the frequency-dependent reference phase, in order to ascertain a second phase change; and

   - to evaluate the first phase change and the second phase change, in particular to compare these to one another.
2. The orthosis or prosthesis system (100) as claimed in claim 1, characterized in that the evaluation unit (10) is configured to evaluate a phase response of the first and second signal.
3. The orthosis or prosthesis system (100) as claimed in any one of the preceding claims , characterized in that the reference phase is a phase (22, 26), in particular a phase determined in advance, which substantially corresponds to a measurement in a relaxed state of a muscle.
4. The orthosis or prosthesis system (100) as claimed in any of the preceding claims, characterized in that the evaluation unit (10) is configured to ascertain whether the first phase change is a phase change in the same direction as the second phase change or in an opposite direction thereto.
5. The orthosis or prosthesis system (100) as claimed in claim 4, characterized in that the evaluation unit (10) is configured to assess the first and second signal as belonging to a muscle contraction if the first and second phase change are phase changes in opposite directions.
6. The orthosis or prosthesis system (100) as claimed in claim 4 or 5, characterized in that the evaluation unit (10) is configured to assess the first and second signal as belonging to a disturbance if the first and second phase change are phase changes in the same direction.
7. The orthosis or prosthesis system (100) as claimed in any one of the preceding claims, characterized in that the first measurement frequency is more than approximately 60 kHz and the second measurement frequency is less than approximately 60 kHz.
8. The orthosis or prosthesis system as claimed in any one of the preceding claims, characterized in that the first measurement frequency is substantially greater than 60 kHz and/or the second measurement frequency is substantially less than 60 kHz.
9. The orthosis or prosthesis system (100) as claimed in any one of the preceding claims, characterized in that the at least first and second muscle-related signal is a bioimpedance signal.
10. The orthosis or prosthesis system (100) as claimed in any one of the preceding claims, characterized in that the at least one electrode pair (11) is further configured to supply electrical stimulation signals to the user of the orthosis or prosthesis.
11. The orthosis or prosthesis system (100) as claimed in claim 10, characterized in that the electrical stimulation signals are configured to provide the user of the orthosis or prosthesis with feedback about the movements and/or the state of the orthosis or prosthesis.

Images